Influence of age and postmenopausal estrogen replacement therapy on carotid arterial stiffness in women

Estrogen-mediated mechanisms in hypertension and other cardiovascular diseases

Cardiovascular disease (CVD) is the leading cause of death globally for men and women. Premenopausal women have a lower incidence of hypertension and other cardiovascular events than men of the same age, but diminished sex differences after menopause implicates 17-beta-estradiol (E2) as a protective agent. The cardioprotective effects of E2 are mediated by nuclear estrogen receptors (ERα and ERβ) and a G protein-coupled estrogen receptor (GPER). This review summarizes both established as well as emerging estrogen-mediated mechanisms that underlie sex differences in the vasculature during hypertension and CVD. In addition, remaining knowledge gaps inherent in the association of sex differences and E2 are identified, which may guide future clinical trials and experimental studies in this field.

Cardiometabolic health, menopausal estrogen therapy and the brain: How effects of estrogens diverge in healthy and unhealthy preclinical models of aging

Research in preclinical models indicates that estrogens are neuroprotective and positively impact cognitive aging. However, clinical data are equivocal as to the benefits of menopausal estrogen therapy to the brain and cognition. Pre-existing cardiometabolic disease may modulate mechanisms by which estrogens act, potentially reducing or reversing protections they provide against cognitive decline. In the current review we propose mechanisms by which cardiometabolic disease may alter estrogen effects, including both alterations in actions directly on brain memory systems and actions on cardiometabolic systems, which in turn impact brain memory systems. Consideration of mechanisms by which estrogen administration can exert differential effects dependent upon health phenotype is consistent with the move towards precision or personalized medicine, which aims to determine which treatment interventions will work for which individuals. Understanding effects of estrogens in both healthy and unhealthy models of aging is critical to optimizing the translational link between preclinical and clinical research.

Is Stiffness Parameter β Useful for the Evaluation of Atherosclerosis?~ Its Clinical Implications, Limitations, and Future Perspectives ~

Atherosclerosis comprises two components, atherosis and sclerosis, characterized by morphological wall thickening and functional stiffening, respectively, of the arterial wall. In recent years, much interest has been directed to the role of functional changes in large arteries, i.e., increased stiffness or decreased elasticity, on the development of cardiovascular diseases. In fact, the clinical evaluation of arterial stiffness is increasingly performed in patients with cardiovascular risk factors. Local arterial stiffness is measured using an ultrasound technique implemented with an echo-tracking system at the common carotid and femoral arteries. Several indices of local arterial stiffness are obtained by ultrasound, among which stiffness parameter β is unique because it is the least affected by blood pressure at the time of measurement. Evidence from cross-sectional studies indicates that increased stiffness parameter β is associated with a number of cardiovascular risk factors, such as older age, smoking, insufficient physical activity, hypertension, obesity, metabolic syndrome, insulin resistance, type 2 diabetes, chronic kidney disease, and comorbid cardiovascular disease. Results from several prospective observational studies also suggest that carotid stiffness parameter β is a useful surrogate marker of cardiovascular events and/or mortality, although the results differ depending on the characteristics of the study subjects. Furthermore, several interventional studies have shown that carotid stiffness parameter β improved after lifestyle modification or drug treatment. In this review, we summarize the current evidence of stiffness parameter β of the carotid artery and discuss its clinical implications as a marker of vascular health or as a predictor of cardiovascular outcomes.

Associations of Sex Hormones and Hormonal Status With Arterial Stiffness in a Female Sample From Reproductive Years to Menopause

OBJECTIVE

Loss of sex hormones has been suggested to underlie menopause-associated increment in cardiovascular risk. We investigated associations of sex hormones with arterial stiffness in 19-58-years-old women. We also studied associations of specific hormonal stages, including natural menstrual cycle, cycle with combined oral contraceptives (COC) and menopausal status with or without hormone therapy (HT), with arterial stiffness.

METHODS

This study includes repeated measurements of 65 healthy women representing reproductive (n=16 natural, n=10 COC-users) and menopause (n=5 perimenopausal, n=26 postmenopausal, n=8 HT-users) stages. Arterial stiffness outcomes were aortic pulse wave velocity (PWVao) and augmentation index (AIx%) assessed using Arteriograph-device. Generalized estimating equation models were constructed to investigate associations of each hormone (wide age-range models) or hormonal stage (age-group focused models) with arterial stiffness. PWVao models with cross-sectional approach, were adjusted for age, relative fitness, fat mass and mean arterial pressure, while models with longitudinal approach were adjusted for mean arterial pressure. AIx% models used the same approach for adjustments and were also adjusted for heart rate.

RESULTS

Negative and positive associations with arterial stiffness variables were observed for estradiol and follicle-stimulating hormone, respectively, until adjustment for confounding effect of age. In naturally menstruating women, AIx% was higher at ovulation (B=3.63, p<0.001) compared to the early follicular phase. In COC-users, PWVao was lower during active (B=-0.33 - -0.57, p<0.05) than inactive pills. In menopausal women, HT-users had higher PWVao (B=1.43, p=0.03) than postmenopausal non-HT-users.

CONCLUSIONS

When using wide age-range assessments covering reproductive to menopausal lifespan it is difficult to differentiate age- and hormone-mediated associations, because age-mediated influence on arterial stiffness seemed to overrule potential hormone-mediated influences. However, hormonal status associated differentially with arterial stiffness in age-group focused analyses. Thus, the role of sex hormones cannot be excluded. Further research is warranted to resolve potential hormone-mediated mechanisms affecting arterial elasticity.

Mechanisms of increased vascular stiffness down the aortic tree in aging, premenopausal female monkeys

Protection against increased vascular stiffness in young women is lost after menopause. However, little is known about vascular stiffness in older, premenopausal females, because most of the prior work has been conducted in rodents, which live for only 1-3 yr and do not go through menopause. The goal of the current investigation was to quantitate differences in stiffness down the aortic tree and the mechanisms mediating those differences in older, premenopausal (24 ± 0.7 yr) versus young adult (7 ± 0.7 yr) female nonhuman primates. Aortic stiffness (β), calculated from direct and continuous measurements of aortic diameter and pressure in chronically instrumented, conscious macaque monkeys, increased 2.5-fold in the thoracic aorta and fivefold in the abdominal aorta in old premenopausal monkeys. The aortic histological mechanisms mediating increased vascular stiffness, i.e., collagen/elastin ratio, elastin, and collagen disarray, and the number of breaks in elastin and collagen fibers were greater in the old premenopausal versus young monkeys and greater in the abdominal versus the thoracic aorta and greatest in the iliac artery. In addition, more immature and less cross-linked fibers of collagen were found in the aortas of young females. Aortic stiffness increased in old premenopausal female monkeys, more so in the abdominal aorta than in the thoracic aorta. Histological mechanisms mediating the increased aortic stiffness were augmented in the old premenopausal females, greater in the abdominal versus the thoracic aorta, and greatest in the iliac artery.NEW & NOTEWORTHY This is the first study to examine vascular stiffness down the aortic tree in aging premenopausal females (24 ± 0.7 yr old), whereas prior work studied mainly rodents, which are short-lived and do not undergo menopause. Histological mechanisms mediating vascular stiffness in older premenopausal females increased progressively down the aortic tree, with greater increases in the abdominal aorta compared with the thoracic aorta and with the greatest increases and differences observed in the iliac artery.

The effect of different estradiol levels on carotid artery distensibility during a long agonist IVF protocol

BACKGROUND

This study was made to figure out, does low and high estradiol levels during in vitro fertilization (IVF) cycles have a different effect on carotid artery distensibility (Cdis), carotid artery diameter (Cdia), blood pressure and metabolic factors? Can the stimulation protocol be considered safe to women's vasculature?

METHODS

We studied 28 women having a long agonist protocol IVF-treatment in Kuopio University Hospital during the years 2011-2016. Patients were examined at three time points: in the beginning of their own period (low estradiol), during the gonadotrophin releasing hormone (GnRH) analogue downregulation (low estradiol) and during the follicle stimulating hormone (FSH) stimulation (high estradiol). Women served as their own controls and their menstrual phase (2- to 5-day period after the beginning of menstruation with low estrogen) was used as the reference. Cdis and Cdia were assessed using ultrasound. Blood pressure, weight, estradiol levels and lipids were monitored.

RESULTS

Cdis, Cdia, systolic and diastolic blood pressures peaked during the GnRH-analogue treatment with the lowest estradiol levels. Cdis, Cdia and systolic blood pressures declined by 11% (P = 0.002), 3,8% (P < 0.001) and 2,5% (P = 0.026) during the FSH-stimulation when the estradiol levels were high. Cdis correlated significantly (P < 0.05) with systolic blood pressure, diastolic blood pressure and triglycerides in high estrogenic environment and with diastolic blood pressure (P < 0.05) when estrogen profiles were low.

CONCLUSIONS

Carotid artery stiffens during the high estradiol levels compared to low levels and this was not explained by the higher diameter of the carotid artery, hyperlipidemia or blood pressure profiles. All the changes in Cdis and Cdia are variations of normal, and if there is no history of cardiovascular problems, it can be considered, that the stimulation protocol is not hazardous to vasculature.

Effects of acute dietary nitrate supplementation on aortic blood pressures and pulse wave characteristics in post-menopausal women

PURPOSE

Consumption of nitrate-rich beetroot juice can lower blood pressure in peripheral as well as central arteries and may exert additional hemodynamic benefits (e.g. reduced aortic wave reflections). The specific influence of nitrate supplementation on arterial pressures and aortic wave properties in postmenopausal women, a group that experiences accelerated increases in these variables with age, is unknown. Accordingly, the primary aim of this study was to determine the effect of consuming nitrate-rich beetroot juice on resting brachial and aortic blood pressures (BP) and pulse wave characteristics in a group of healthy postmenopausal women, in comparison to a true (nitrate-free beetroot juice) placebo.

METHODS

Brachial (oscillometric cuff) and radial (SphygmoCor) pressures and derived-aortic waveforms were measured during supine rest in thirteen healthy postmenopausal women (63 ± 1 yr) before and 100 min after consumption of 140 ml of either nitrate-rich (9.7 mmol, 0.6 gm NO₃^-) or nitrate-depleted beetroot juice on randomized visits approximately 10 days apart (cross-over design). Ten young premenopausal women (22 ± 1 yr) served as a reference (non-supplemented) cohort.

RESULTS

Brachial and derived-aortic variables showed the expected age-associated differences in these women (all p < 0.05). In post-menopausal women, nitrate supplementation reduced (p < 0.05 vs. placebo visit) brachial systolic BP (BR_nitrate -4.9 ± 2.1 mmHg vs BR_placebo +1.1 ± 1.8 mmHg), brachial mean BP (BR_nitrate -4.1 ± 1.7 mmHg vs BR_placebo +0.9 ± 1.3 mmHg), aortic systolic BP (BR_nitrate -6.3 ± 2.0 mmHg vs BR_placebo +0.5 ± 1.7 mmHg) and aortic mean BP (BR_nitrate -4.1 ± 1.7 mmHg vs BR_placebo +0.9 ± 1.3 mmHg), and increased pulse pressure amplification (BR_nitrate +4.6 ± 2.0% vs BR_placebo +0.7 ± 2.5%, p = 0.04), but did not alter aortic pulse wave velocity or any other derived-aortic variables (e.g., augmentation pressure or index).

CONCLUSIONS

Dietary nitrate supplementation favorably modifies aortic systolic and mean blood pressure under resting conditions in healthy postmenopausal women. Acute supplementation of nitrate does not, however, appear to restore indices of aortic stiffness in this group. Future work should evaluate chronic, long-term effects of this non-pharmacological supplement.

Intersection between gonadal function and vascular aging in women

Vascular aging, characterized by endothelial dysfunction and large elastic arterial stiffening, is a major risk factor for age-associated cardiovascular disease (CVD). Although women have a lower prevalence of CVD until midlife, prevalence rates increase rapidly coincident with the menopausal transition to match those observed in men. The menopausal transition, or perimenopause, is a chaotic period that is associated with increased symptoms (e.g., hot flashes, depressed mood, anxiety, sleep disturbances) and CVD risk factors due to changes in the hormonal environment. Because these quality of life factors and CVD risk factors also change with aging, the arteries of women appear to endure a double insult. Our laboratory has been investigating how changes in gonadal function and hormone levels with the menopause transition impacts the vascular aging process in healthy women. Our work has shown that vascular endothelial function progressively declines, and large elastic arterial stiffness is greater across the stages of the menopausal transition. This acceleration in vascular aging may be due to the loss of vasodilatory, antioxidant, anti-inflammatory, and antiproliferative effects of estradiol on the vascular wall. This minireview discusses the impact of changes in gonadal function and hormones with the menopausal transition on vascular aging in women and areas for investigations to further our understanding of the intersection between gonadal function and vascular aging.

Relation of Sex Hormone Levels With Prevalent and 10-Year Change in Aortic Distensibility Assessed by MRI: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Women experience a steeper decline in aortic elasticity related to aging compared to men. We examined whether sex hormone levels were associated with ascending aortic distensibility (AAD) in the Multi-Ethnic Study of Atherosclerosis.

METHODS

We studied 1,345 postmenopausal women and 1,532 men aged 45-84 years, who had serum sex hormone levels, AAD measured by phase-contrast cardiac magnetic resonance imaging, and ejection fraction>50% at baseline. Among these participants, 457 women and 548 men returned for follow-up magnetic resonance imaging 10-years later. Stratified by sex, and using mixed effects linear regression methods, we examined associations of sex hormones (as tertiles) with baseline and annual change in log-transformed AAD (mm Hg-110-3), adjusting for demographics, body size, lifestyle factors, mean arterial pressure, heart rate, hypertensive medication use (and in women, for hormone therapy use and years since menopause).

RESULTS

The mean (SD) age was 65 (9) for women and 62 (10) years for men. AAD was lower in women than men (P < 0.001). In adjusted cross-sectional analysis, the highest tertile of free testosterone (compared to lowest) in women was significantly associated with lower AAD [-0.10 (-0.19, -0.01)] and the highest tertile of estradiol in men was associated with greater AAD [0.12 (0.04, 0.20)]. There were no associations of sex hormones with change in AAD over 10 years, albeit in a smaller sample size.

CONCLUSIONS

Lower free testosterone in women and higher estradiol in men were associated with greater aortic distensibility at baseline, but not longitudinally. Sex hormone levels may account for differences in AAD between women and men.

Association between endothelial dysfunction, epicardial fat and subclinical atherosclerosis during menopause

BACKGROUND

Menopausal transition is critical for the development of early, subclinical vascular damage. Multiple factors, such as atherosclerosis, increased epicardial fat, and endothelial dysfunction can play a role. Hence, the objective of this study was the comparison of epicardial adipose tissue and carotid intima media thickness in order to establish the best predictor of carotid stiffness in middle-aged women with endothelial dysfunction.

METHODS

A total of 43 healthy women aged 40-59 years old with endothelial dysfunction previously demonstrated by flow mediated dilation were recruited to have anthropometric, biochemical, hormonal and ultrasound determinations of carotid intima media thickness and epicardial fat thickness.

RESULTS

Carotid arterial stiffness parameters (local pulse wave velocity [4.7±0.7 vs 4.8±0.5 vs 5.6±0.5m/s, respectively, p<0.001], pressure strain elastic modulus [55.2±13.4 vs 59.2±11.8 vs 81.9±15.6kPa, respectively, p<0.001], arterial stiffness index β [4.4±1.4 vs 5.0±1.1 vs 6.4±1.3, respectively, p<0.001]) and epicardial fat thickness (2.98±1.4 vs 3.28±1.9 vs 4.70±1.0mm, respectively, p=0.007) showed a significant and proportional increase in the group of late post-menopausal women when compared to early post-menopausal and pre-menopausal groups, respectively. Among body fat markers, epicardial fat was the strongest predictor of local pulse wave velocity, independent of age.

CONCLUSIONS

In menopausal women with endothelial dysfunction, menopausal transition is associated with increased carotid arterial stiffness and epicardial fat thickness, independent of age. Ultrasound measured epicardial fat was a better independent predictor of arterial stiffness than carotid intima media thickness in these women.

Endothelial Estrogen Receptor-α Does Not Protect Against Vascular Stiffness Induced by Western Diet in Female Mice

Consumption of a diet high in fat and refined carbohydrates (Western diet [WD]) is associated with obesity and insulin resistance, both major risk factors for cardiovascular disease (CVD). In women, obesity and insulin resistance abrogate the protection against CVD likely afforded by estrogen signaling through estrogen receptor (ER)α. Indeed, WD in females results in increased vascular stiffness, which is independently associated with CVD. We tested the hypothesis that loss of ERα signaling in the endothelium exacerbates WD-induced vascular stiffening in female mice. We used a novel model of endothelial cell (EC)-specific ERα knockout (EC-ERαKO), obtained after sequential crossing of the ERα double floxed mice and VE-Cadherin Cre-recombinase mice. Ten-week-old females, EC-ERαKO and aged-matched genopairs were fed either a regular chow diet (control diet) or WD for 8 weeks. Vascular stiffness was measured in vivo by pulse wave velocity and ex vivo in aortic explants by atomic force microscopy. In addition, vascular reactivity was assessed in isolated aortic rings. Initial characterization of the model fed a control diet did not reveal changes in whole-body insulin sensitivity, aortic vasoreactivity, or vascular stiffness in the EC-ERαKO mice. Interestingly, ablation of ERα in ECs reduced WD-induced vascular stiffness and improved endothelial-dependent dilation. In the setting of a WD, endothelial ERα signaling contributes to vascular stiffening in females. The precise mechanisms underlying the detrimental effects of endothelial ERα in the setting of a WD remain to be elucidated.

Estrogen Replacement Therapy in Ovariectomized Nonpregnant Ewes Stimulates Uterine Artery Hydrogen Sulfide Biosynthesis by Selectively Up-Regulating Cystathionine β-Synthase Expression

Estrogens dramatically dilate numerous vascular beds with the greatest response in the uterus. Endogenous hydrogen sulfide (H2S) is a potent vasodilator and proangiogenic second messenger, which is synthesized from L-cysteine by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE). We hypothesized that estrogen replacement therapy (ERT) selectively stimulates H2S biosynthesis in uterine artery (UA) and other systemic arteries. Intact and endothelium-denuded UA, mesenteric artery (MA), and carotid artery (CA) were obtained from ovariectomized nonpregnant ewes (n = 5/group) receiving vehicle or estradiol-17β replacement therapy (ERT). Total RNA and protein were extracted for measuring CBS and CSE, and H2S production was determined by the methylene blue assay. Paraffin-embedded UA rings were used to localize CBS and CSE proteins by immunofluorescence microscopy. ERT significantly stimulated CBS mRNA and protein without altering CSE mRNA or protein in intact and denuded UA. Quantitative immunofluorescence microscopic analyses showed CBS and CSE protein localization in endothelium and smooth muscle and confirmed that ERT stimulated CBS but not CSE protein expression in UA endothelium and smooth muscle. ERT also stimulated CBS, but not CSE, mRNA and protein expression in intact and denuded MA but not CA in ovariectomized ewes. Concomitantly, ERT stimulated UA and MA but not CA H2S production. ERT-stimulated UA H2S production was completely blocked by a specific CBS but not CSE inhibitor. Thus, ERT selectively stimulates UA and MA but not CA H2S biosynthesis by specifically up-regulating CBS expression, implicating a role of H2S in estrogen-induced vasodilation and postmenopausal women's health.

Oxidative stress contributes to large elastic arterial stiffening across the stages of the menopausal transition

OBJECTIVE

It is unclear how changes in ovarian hormones during the menopausal transition contribute to age-associated arterial stiffening. We sought to evaluate differences in arterial stiffness and the role of oxidative stress across the stages of the menopausal transition in healthy women.

METHODS

Arterial stiffness (carotid artery compliance and ultrasound) was measured during immediate infusions of saline (control) and ascorbic acid (experimental model to immediately decrease oxidative stress) in 97 healthy women (22-70 y) classified as premenopausal (n = 24; mean [SD] age, 33 [7] y), early perimenopausal (n = 21; 49 [3] y) or late perimenopausal (n = 21; 50 [4] y), or postmenopausal (n = 31; 57 [5] y).

RESULTS

Basal carotid artery compliance was different among the groups (P < 0.001). Mean [SD] compliance was highest in premenopausal women (1.31 [0.25] mm/mm Hg × 10), with progressive decrements in perimenopausal (early perimenopausal, 0.98 [0.31] mm/mm Hg × 10; late perimenopausal, 0.90 [0.25] mm/mm Hg × 10) and postmenopausal (0.75 [0.24] mm/mm Hg × 10) women. Ascorbic acid infusion improved compliance in late perimenopausal (15% [18%] increase, P = 0.001) and postmenopausal (17% [26%] increase, P = 0.002) women but not in early perimenopausal or premenopausal women.

CONCLUSIONS

Arterial stiffening worsens across the stages of the menopausal transition in healthy women. This seems to be mediated, in part, by oxidative stress, particularly during the late perimenopausal and postmenopausal periods. It remains uncertain whether this is specifically caused by loss of ovarian function or aging.

Vascular Aging across the Menopause Transition in Healthy Women

Vascular aging, featuring endothelial dysfunction and large artery stiffening, is a major risk factor for developing cardiovascular disease (CVD). In women, vascular aging appears to be accelerated during the menopause transition, particularly around the late perimenopausal period, presumably related to declines in ovarian function and estrogen levels. The mechanisms underlying endothelial dysfunction and large artery stiffening with the menopause transition are not completely understood. Oxidative stress and the proinflammatory cytokine tumor necrosis factor-α contribute to endothelial dysfunction and large artery stiffening in estrogen-deficient postmenopausal women. Habitual endurance exercise attenuates the age-related increase in large artery stiffness in estrogen-deficient postmenopausal women and can reverse arterial stiffening to premenopausal levels in estrogen-replete postmenopausal women. In contrast, estrogen status appears to play a key permissive role in the adaptive response of the endothelium to habitual endurance exercise in that endothelial improvements are absent in estrogen-deficient women but present in estrogen-replete women. We review here the current state of knowledge on the biological defects underlying vascular aging across the menopause transition, with particular focus on potential mechanisms, the role of habitual exercise in preserving vascular health, and key areas for future research.

Tumor necrosis factor-α inhibition improves endothelial function and decreases arterial stiffness in estrogen-deficient postmenopausal women

OBJECTIVE

Tumor necrosis factor (TNF)-α, a pleiotropic pro-inflammatory cytokine involved in a variety of biological processes including oxidative stress, has been associated with vascular dysfunction in aged and ovariectomized animals. We determined whether acute inhibition of TNF-α improves vascular endothelial function and decreases arterial stiffness in estrogen-deficient postmenopausal women.

METHODS

Arterial stiffness (carotid artery compliance) and endothelial function (brachial artery flow-mediated dilation [FMD]) were measured in postmenopausal women (n = 23; 57 ± 1 years, mean ± SE) before and following randomization to two days of either transdermal estradiol (0.05 mg/d, N = 12) or placebo (N = 11) alone and following a single subcutaneous injection of the TNF-α inhibitor, etanercept (25 mg), and in premenopausal (n = 9; 33 ± 2 years) before and following etanercept.

RESULTS AND CONCLUSIONS

Baseline carotid artery compliance and brachial artery FMD were lower in postmenopausal than premenopausal women (P < 0.0001). In postmenopausal women, carotid artery compliance (n = 12; 0.59 ± 0.05-0.78 ± 0.06 mm(2)/mmHg × 10(-1), P < 0.001) and FMD (4.1 ± 0.6-6.0 ± 0.7%, P = 0.02) increased in response to estradiol but not placebo (n = 11). Carotid artery compliance (0.71 ± 0.06-0.81 ± 0.06 mm(2)/mmHg × 10(-1), P = 0.02) and FMD (5.2 ± 0.7-7.5 ± 0.9%, P = 0.003) increased with etanercept in the placebo group but had no effect in postmenopausal randomized to estradiol or premenopausal women. These results suggest that TNF-α contributes to impaired endothelial-dependent vasodilation and arterial stiffening in estrogen-deficient postmenopausal women.

Arterial stiffness, carotid atherosclerosis and left ventricular diastolic dysfunction in postmenopausal women

BACKGROUND

Postmenopausal women have an increased cardiovascular morbidity that may be due to the increase in classical cardiovascular risk factors and also to the arterial structure and function alterations. The aim of our study was to evaluate the association of aortic pulse wave velocity (PWV), and carotid intima-media thickness (IMT), with left ventricular diastolic dysfunction (LVDD) in postmenopausal women.

PATIENTS AND METHODS

In 96 women without overt cardiovascular disease (age 62±7.7 years), and with normal left ventricular systolic function, aortic PWV was assessed by using an oscillometric device, intima-media thickness was measured by B-mode ultrasonography and the parameters of left ventricular diastolic function were evaluated by a transthoracic echocardiographic study.

RESULTS

LVDD, defined as an E/A ratio≤1 was found in 50 patients (52%). All of them had mild LVDD. In these patients we found significant increase in age (p<0.001), aortic PWV (p<0.001), carotid IMT (p=0.002) and plaque score (p=0.004) when compared with patients without LVDD. In a logistic regression analyzed, after adjusting for age, only aortic PWV was a significant predictor of LVDD (2.15, 95% CI 1.39-3.31, p=0.0006).

CONCLUSIONS

This study among postmenopausal women provides evidence that increased arterial stiffness as measured by aortic PWV and not carotid IMT may be a marker or a risk factor for LVDD, independent of other classical risk factors.

Pulse Wave Velocity in Postmenopausal Women

Cardiovascular disease (CVD) and osteoporosis are major causes of morbidity and mortality in postmenopausal women. The relationship between atherosclerosis and osteoporosis has been established by studies of the underlying pathophysiological mechanisms and biochemical pathways that seem to overlap in many places. Pulse wave velocity (PWV) is one of the known predictors of cardiovascular and all-cause mortality. Studies indicate that PWV in hypertensive postmenopausal women is increased, and hormone replacement therapy (HRT) attenuates this increase. In addition, recently, many studies have suggested a role for arterial stiffness in the association between CVD and osteoporosis. From these findings, it appears that estrogen deficiency combined with production of inflammatory cytokines plays a role in increased PWV closely associated with CVD and osteoporosis, although the mechanisms of arterial stiffness in postmenopausal women may be more complex. Accordingly, a possible role for PWV as a surrogate marker of CVD as well as osteoporosis in postmenopausal women is discussed in this review. First, menopause leads to increased arterial stiffness with aging in females. Further, epidemiological data evaluating arterial stiffness assessed by PWV provided evidence that most of the established CVD risk factors are determinants of PWV, and these risk factors are increased in patients with CVD. In turn, contrary to expectation, HRT did not always contribute to a lower incidence of CVD in postmenopausal women. By reviewing the current data available, it becomes clear that, at present, the effects of menopause including HRT on PWV remain controversial, and further studies are needed to clarify these associations.

Window of opportunity: estrogen as a treatment for ischemic stroke

The neuroprotection research in the last 2 decades has witnessed a growing interest in the functions of estrogens as neuroprotectants against neurodegenerative diseases including stroke. The neuroprotective action of estrogens has been well demonstrated in both in vitro and in vivo models of ischemic stroke. However, the major conducted clinical trials so far have raised concern for the protective effect of estrogen replacement therapy in postmenopausal women. The discrepancy could be partly due to the mistranslation between the experimental stroke research and clinical trials. While predominant experimental studies tested the protective action of estrogens on ischemic stroke using acute treatment paradigm, the clinical trials have mainly focused on the effect of estrogen replacement therapy on the primary and secondary stroke prevention which has not been adequately addressed in the experimental stroke study. Although the major conducted clinical trials have indicated that estrogen replacement therapy has an adverse effect and raise concern for long term estrogen replacement therapy for stroke prevention, these are not appropriate for assessing the potential effects of acute estrogen treatment on stroke protection. The well established action of estrogen in the neurovascular unit and its potential interaction with recombinant tissue Plasminogen Activator (rtPA) makes it a candidate for the combined therapy with rtPA for the acute treatment of ischemic stroke. On the other hand, the "critical period" and newly emerged "biomarkers window" hypotheses have indicated that many clinical relevant factors have been underestimated in the experimental ischemic stroke research. The development and application of ischemic stroke models that replicate the clinical condition is essential for further evaluation of acute estrogen treatment on ischemic stroke which might provide critical information for future clinical trials. This article is part of a Special Issue entitled Hormone Therapy.

Hysterectomy is associated with large artery stiffening in estrogen-deficient postmenopausal women

OBJECTIVE

Hysterectomy, with or without oophorectomy, is associated with increased cardiovascular disease (CVD) risk due, in part, to an adverse CVD risk factor profile. Large artery stiffening, a biomarker of vascular aging, increases the risk for CVD. We determined whether hysterectomy with or without bilateral oophorectomy (BLO) is associated with arterial stiffening in healthy postmenopausal women.

METHODS

We conducted a cross-sectional study including estrogen-deficient postmenopausal women who had a hysterectomy with ovarian preservation (n = 24; mean ± SE age, 59 ± 1 y) or with BLO (n = 21; 58 ± 2 y) and had no hysterectomy/no BLO (n = 58; 58 ± 1 y). Arterial stiffness (arterial compliance and β stiffness index) was measured by ultrasonography of the carotid artery.

RESULTS

Carotid artery compliance was lower in women with hysterectomy alone and in women with hysterectomy with BLO compared with women with no hysterectomy (0.66 ± 0.03 and 0.71 ± 0.06 vs 0.89 ± 0.03 mm/mm Hg × 10, respectively, both P < 0.05). There were no differences in traditional CVD risk factors (ie, adiposity, blood pressure and fasted lipids and lipoproteins, glucose, and insulin) between the groups. After adjustment for age, menopause duration, previous menopausal hormone therapy duration, parity, waist-to-hip ratio, systolic blood pressure, and sex hormone-binding globulin, hysterectomy status remained a significant predictor of arterial compliance.

CONCLUSIONS

These results indicate that hysterectomy status (with or without BLO) is associated with greater arterial stiffening in estrogen-deficient postmenopausal women. The greater arterial stiffening with hysterectomy was not related to an adverse CVD risk profile. Large artery stiffening may be an important mechanism by which hysterectomy increases the risk of CVD in postmenopausal women.

Tetrahydrobiopterin improves endothelial function and decreases arterial stiffness in estrogen-deficient postmenopausal women

The mechanisms mediating arterial stiffening with aging and menopause are not completely understood. We determined whether administration of tetrahydrobiopterin (BH(4)), a critical cofactor for endothelial nitric oxide synthase to produce nitric oxide, would increase vascular endothelial-dependent vasodilatory tone and decrease arterial stiffness in estrogen-deficient postmenopausal women. Additionally, we examined whether the beneficial effects of estrogen on vascular function were possibly related to BH(4). Arterial stiffness (carotid artery compliance) and endothelial-dependent vasodilation [brachial artery flow-mediated dilation (FMD)] were measured in postmenopausal (n = 24; 57 ± 1 yr, mean ± SE) and eumenorrheic premenopausal (n = 9; 33 ± 2 yr) women before and 3 h after the oral administration of BH(4). Subsequently, in postmenopausal women, vascular testing (before and after BH(4)) was repeated following randomization to either 2 days of transdermal estradiol or placebo. Baseline carotid artery compliance and brachial artery FMD were lower in postmenopausal than in premenopausal women (P < 0.0001). BH(4) administration increased carotid artery compliance (0.61 ± 0.05 to 0.73 ± 0.04 mm(2)·mmHg(-1)·10(-1) vs. baseline, P < 0.0001) and brachial artery FMD (P < 0.001) in postmenopausal women but had no effect in premenopausal women (P = 0.62). Carotid artery compliance (0.59 ± 0.05 to 0.78 ± 0.06 mm(2)·mmHg(-1)·10(-1), P < 0.001) and FMD increased in postmenopausal women in response to estradiol (P = 0.02) but were not further improved with the coadministration of BH(4), possibly because estrogen increased BH(4) bioavailability. Carotid artery compliance and FMD increased with BH(4) in the placebo group (P = 0.02). Although speculative, these results suggest that reduced vascular BH(4) may be an important contributor to arterial stiffening in estrogen-deficient postmenopausal women, related in part to reduced endothelial-dependent vasodilatory tone.

Association of menopause and hormone replacement therapy with large artery remodeling

OBJECTIVE

To evaluate the remodeling of large arteries according to age at menopause, duration of menopause, and use of hormone therapy (HT).

DESIGN

A cross-sectional study consisting of baseline measurements of a multicentric randomized trial were used to evaluate arterial parameters.

SETTING

The study was conducted in France, Belgium, and the Netherlands in academic hospitals and private clinics.

PATIENT(S)

Postmenopausal women (n = 538) with mild hypercholesterolemia.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Common carotid artery intima-media thickness (CCA-IMT), central pulse pressure, and aortic stiffness (carotid-femoral pulse wave velocity) were measured and centrally controlled for quality. Multivariate regression analysis was used to assess the possible covariates associated with arterial parameters.

RESULT(S)

Women were 58 ± 6 (mean ± SD) years of age with an age of 50 ± 5 at menopause and a mean duration of menopause of 8 ± 7 years. Lower age at menopause, time since menopause, and absence of HT use were independently associated with worsening of the arterial parameters. After multivariate analysis, HT was associated with a lower CCA-IMT (-40 μm [range -64 to -1]), whereas lower age at menopause and menopause duration were respectively associated with a CCA-IMT increase (25 μm/5 y and 27 μm/5 y). Similarly, values of central pulse pressure and pulse wave velocity were lower in HT users (-3.1 mm Hg [-5.1 to -0.9] and -0.31 m/s [-0.63 to -0.02], respectively) but worsened with age at menopause and menopause duration.

CONCLUSION(S)

The age at menopause, the time since menopause, and the use of HT are independently associated with the thickening and stiffening of the large arteries.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00163163.

Acute effects of warm footbath on arterial stiffness in healthy young and older women

Acute systemic thermal therapy can improve arterial stiffness in both animals and humans. We examined and compared the effects of acute local thermal therapy (footbath) on an indicator of human arterial stiffness, cardio-ankle vascular index (CAVI), in 16 healthy young (29.4 ± 0.4 years) and 16 older (59.8 ± 1.7 years) women. Measurements were made at baseline (BL) and at 0 and 30 min after footbath in footbath trial, and at corresponding time points without footbath in control trial. In the footbath trial, subjects immersed their lower legs and feet in water for 30 min, with water temperature ranging from 41 to 43°C. The results showed that footbath elicited significant reductions in CAVI at 0 min compared to the same trial's baseline in both young and older groups (0.55 ± 0.07, P = 0.01 for young; 0.42 ± 0.15, P = 0.03 for older, respectively) with no changes found in the control trials. The percentage of CAVI change at 0 min was significantly greater in young women (91.9 ± 1.1%) compared to older women (96.5 ± 1.8%, P < 0.05). This study indicated that acute warm footbath results in transient improvement of systemic arterial stiffness in both healthy young and older women. Despite similar intervention, the percentage response of arterial stiffness to footbath was attenuated in older women.

Does hormone treatment alter arterial properties in postmenopausal women?

Arterial elastic properties and wave reflections constitute left ventricular pulsatile afterload and are directly related to cardiovascular morbidity and mortality. During the aging process, elastic arteries stiffen and increase pulse wave velocity, causing the reflected pressure wave to arrive at the heart during systole, and augment systolic and pulse blood pressure, resulting in left ventricular hypertrophy. The incidence of cardiovascular disease is much greater in men aged 30-50 years compared with women of a similar age. Among women, the incidence of cardiovascular disease increases dramatically after menopause, which occurs at an average age of 52 years. This observation has lead to the belief that sex hormones produced premenopausally impede or delay the progression of cardiovascular disease. Therefore, it appears logical that the administration of female sex hormones, hormone treatment (HT), estrogen alone or with progesterone should provide some degree of cardiovascular protection. This idea was supported by experiments in animals and isolated arterial segments demonstrating that HT increases plasma nitric oxide, decreases endothelin-1 levels and causes smooth muscle relaxation. Also, 17β-estradiol administration decreases collagen and increases elastin in the aortic wall of rats. These experimental studies suggest an improvement in both elastic and muscular artery properties and favorabe modifications of arterial wave reflection characteristics. Furthermore, HT improves lipoprotein metabolism and reduces coronary artery plaque formation in animal models. Unfortunately, observational and interventional studies in postmenopausal women that have evaluated the impact of HT on cardiovascular changes have produced inconsistent and inconclusive results. Most studies agree that arterial stiffness increases after menopause, partly due to advancing age and reduced estrogen production. Results from most studies that were designed to investigate the effects of HT on arterial properties have shown a selective decrease in elastic artery stiffness with little effect on muscular arteries. This beneficial effect was observed only if estrogen alone was administered. The main objective of this review is to discuss the ill effects of arterial stiffness in general and attempt to translate information from previous experimental studies to those in postmenopausal women and explain the beneficial effects of HT on arterial stiffness and improvement in left ventricular afterload.

Temocapril, an Angiotensin converting enzyme inhibitor, ameliorates age-related increase in carotid arterial stiffness in normotensive subjects

BACKGROUND/AIMS

Oxidative stress plays an important role in vascular ageing. The close relationship of the renin-angiotensin system with mechanisms of oxidative stress suggests its possible involvement in the deleterious effects of ageing. The present study was designed to investigate whether inhibition of the renin-angiotensin system improves the age-related increase in arterial stiffness.

METHODS

Normotensive elderly subjects in a geriatric nursing home (n = 24; male/female = 7/17; 86 +/- 9 years, mean +/- SD) were randomly assigned to receive either an angiotensin converting enzyme inhibitor, temocapril (n = 12, 1 mg daily) or nothing (n = 12). Carot id arterial stiffness parameter beta and circulating levels of malondialdehyde-modified low-density lipoprotein were measured before and 6 months after randomization.

RESULTS

Temocapril decreased beta (from 7.0 +/- 1.0 to 4.9 +/- 0.9, p < 0.05) and malondialdehyde-modified low-density lipoprotein levels (from 73.2 +/- 19.9 to 61.3 +/- 18.4 U/l, p < 0.05) without changing the blood pressure. The changes in beta and malondialdehyde-modified low-density lipoprotein levels were significantly correlated (rho = 0.600, p < 0.05).

CONCLUSION

These results suggest that temocapril ameliorates the age-related increase in carotid arterial stiffness in healthy, normotensive elderly subjects.

Relationship between androgenic hormones and arterial stiffness, based on longitudinal hormone measurements

Circulating testosterone levels (T) decrease with age in men. Low T has been associated with coronary disease and with risk factors for atherosclerosis. This study examines the relationship in men between androgenic hormones and arterial stiffness, a major risk factor for cardiovascular events. T, sex hormone-binding globulin (SHBG), and dehydroepiandrosterone sulfate (DHEAS) were measured longitudinally over 33 yr (follow-up 11.8 +/- 8.3 yr) in 901 men from the Baltimore Longitudinal Study of Aging, of whom 206 (68.1 +/- 13.7 yr) underwent carotid duplex ultrasonography. The 901 men were used to characterize age-associated hormone levels by means of mixed-effects models. Hormone values were estimated for the 206 men at the time of ultrasonography. Free T index (FTI) was calculated by dividing T by SHBG. The arterial stiffness index was calculated from peak systolic and end diastolic diameters of the common carotid artery and simultaneous brachial artery blood pressure. T, FTI, and DHEAS were correlated negatively with age, pulse pressure (PP), and stiffness index (each P < 0.01), whereas SHBG was correlated positively with age and stiffness index (P < 0.01). However, T was the only hormone that predicted the stiffness index after adjustment for age, PP, fasting plasma glucose, body mass index, and total cholesterol. T values 5-10 yr before the carotid study also predicted the stiffness index (P < 0.05). Thus the adverse influence of low T on the cardiovascular system in men may be mediated in part via the effects of T on vascular structure and function.

Deficiencies in estrogen-mediated regulation of cerebrovascular homeostasis may contribute to an increased risk of cerebral aneurysm pathogenesis and rupture in menopausal and postmenopausal women

Despite the catastrophic consequence of ruptured intracranial aneurysms, very little is understood regarding their pathogenesis, and there are no reliable predictive markers for identifying at-risk individuals. Few studies have addressed the molecular pathological basis and mechanisms of intracranial aneurysm formation, growth, and rupture. The pathogenesis and rupture of cerebral aneurysms have been associated with inflammatory processes, and these have been implicated in the digestion and breakdown of vascular wall matrix. Epidemiological data indicate that the risk of cerebral aneurysm pathogenesis and rupture in women rises during and after menopause as compared to premenopausal women, and has been attributed to hormonal factors. Moreover, experimental evidence supports a role for estrogen in the modulation of each phase of the inflammatory response implicated in cerebral aneurysm pathogenesis and rupture. While the risk of aneurysm rupture in men also increases with age, this increased risk has been attributed to other recognized risk factors including cigarette smoking, use of alcohol, and history of hypertension, all of which are more common in men than women. We hypothesize, therefore, that decreases in both circulating estrogen levels and cerebrovascular estrogen receptor density may contribute to an increased risk of cerebral aneurysm pathogenesis and rupture in women during and after menopause. To test our hypothesis, experiments are needed to identify genes regulated by estrogen and to evaluate gene expression and intracellular mechanisms in cells/tissues exposed to varying concentrations and duration of treatment with estrogen, metabolites of estrogen, and selective estrogen receptor modulators (SERMs). Furthermore, it is not likely that the regulation of cerebrovascular homeostasis is due to the actions of estrogen alone, but rather the interplay of estrogen and other hormones and their associated receptor expression. The potential interactions of these hormones in the maintenance of normal cerebrovascular tone need to be elucidated. Additional studies are needed to define the role that estrogen and other sex hormones may play in the cerebrovascular circulation and the pathogenesis and rupture of cerebral aneurysms. Efforts directed at understanding the basic pathophysiological mechanisms of aneurysm pathogenesis and rupture promise to yield dividends that may have important therapeutic and clinical implications. The development of non-invasive tools such as molecular MRI for the detection of specific cells, molecular markers, and tissues may facilitate early diagnosis of initial pathophysiological changes that are undetectable by clinical examination or other diagnostic tools, and can also be used to evaluate the state of activity of cerebral aneurysm pathogenesis before, during, and after treatment.

Ascorbic acid selectively improves large elastic artery compliance in postmenopausal women

The compliance of large elastic arteries in the cardiothoracic region decreases with advancing age/menopause and plays an important role in the increased prevalence of cardiovascular diseases in postmenopausal women. We determined whether oxidative stress contributes to the reduced large elastic artery compliance of postmenopausal women. Carotid artery compliance was measured during acute intravenous infusions of saline (baseline control) and supraphysiological doses of the potent antioxidant ascorbic acid in premenopausal (n=10; 23+/-1; mean+/-SE) and estrogen-deficient postmenopausal (n=21; 55+/-1 years) healthy sedentary women. Carotid artery compliance was 56% lower in postmenopausal compared with premenopausal women during baseline control (P<0.0001). Ascorbic acid infusion increased carotid artery compliance by 26% in postmenopausal women (1.11+/-0.07 to 1.38+/-0.08 mm2/mm Hgx10(-1); P<0.001) but had no effect in premenopausal women (2.50+/-0.25 versus 2.43+/-0.20 mm2/mm Hgx10(-1)). Carotid artery diameter, blood pressure, and heart rate were unaffected by ascorbic acid. In the pooled population, the change in arterial compliance with ascorbic acid correlated with baseline waist-to-hip ratio (r=0.56; P=0.001), plasma norepinephrine (r=0.58; P=0.001), and LDL cholesterol (r=0.54; P=0.001). These results suggest that oxidative stress may be an important mechanism contributing to the reduced large elastic artery compliance of sedentary, estrogen-deficient postmenopausal women. Increased abdominal fat storage, sympathetic nervous system activity, and LDL cholesterol may be mechanistically involved in oxidative stress-associated suppression of arterial compliance in postmenopausal women.

Effect of light-to-moderate alcohol consumption on age-associated arterial stiffening

Increased thickness and stiffness of large arteries may contribute to why aging is the most important risk for cardiovascular diseases. Arterial stiffness, intimal medial thickness, and alcohol intake were measured in 563 subjects. A U-shaped relation was found between alcohol intake and a stiffness index, with the lowest index in moderate drinkers, which may partially explain the relation between alcohol and cardiovascular disease.

Cerebral Haemodynamics in the Elderly: The Rotterdam Study

Transcranial Doppler ultrasonography allows the non-invasive assessment of cerebral haemodynamics. Data on the frequency distribution of these parameters in the oldest old are scarce, which makes a distinction between physiological and pathophysiological ageing difficult. We studied the relation between cerebral haemodynamic parameters and age and sex in 1,720 participants of a population-based study by means of transcranial Doppler ultrasonography. The end-diastolic, peak systolic and mean cerebral blood flow velocity, and cerebrovascular CO2 reactivity declined significantly with increasing age up to 90 years (per year -0.6 cm/s; -0.3 cm/s; -0.5 cm/s, and -0.6%/kPa, respectively). The pulsatility index increased with age (per year 0.01). End-diastolic, peak systolic and mean cerebral blood flow velocities were lower in men compared to women (age-adjusted difference 1.6 cm/s; 4.1 cm/s, and 2.5 cm/s, respectively). Cerebrovascular CO2 reactivity was higher in men compared to women. Adjusting for carotid atherosclerosis did not change the observed sex differences. These findings provide insight into physiologic changes of haemodynamics during ageing and may serve as a starting point for investigations on determinants of pathophysiologic changes in cerebral haemodynamics in the elderly.

Should Progestins Be Blamed for the Failure of Hormone Replacement Therapy to Reduce Cardiovascular Events in Randomized Controlled Trials?

Many observational studies and experimental and animal studies have demonstrated that estrogen replacement therapy (ERT) or hormone replacement therapy (HRT) (estrogen plus progestin) significantly reduces the risk of coronary heart disease. Nonetheless, recent randomized controlled trials demonstrated some trends toward an increased risk of cardiovascular events rather than a reduction of risk. Recently, both the HRT and ERT arms of the Women’s Health Initiative (WHI) study were terminated early because of an increased/no incidence of invasive breast cancer, increased incidence of stroke, and increased trend/no protective effects of cardiovascular disease. We discuss the controversial effects of HRT and ERT on cardiovascular system and provide a hypothesis that the failure of HRT and ERT in reducing the risk of cardiovascular events in postmenopausal women might be because of the stage of their atherosclerosis at the time of initiation of HRT or ERT.

Can a healthy endothelium influence the cardiovascular effects of hormone replacement therapy?

Emerging clinical and observational evidences suggest that estrogen confers physiologic benefits that are receptor mediated and depend on the integrity and functional status of the endothelium within the coronary vasculature. In postmenopausal women, estrogen replacement therapy (ERT) and hormone replacement therapy (HRT) regimens can enhance the lipoprotein panel; blunt the expression of numerous cytokines, chemokines, and other proinflammatory mediators of endothelial injury and vascular smooth muscle cell proliferation; up-regulate endothelial nitric oxide synthase activity and nitric oxide production; and augment fibrinolysis potential and vasodilator capacity (diminish arterial resistance). Advancing age and atherosclerotic injury to the vessel wall tend to deplete estrogen receptors, compromise endothelial function, promote thrombus formation, and thus potentially diminish the efficacy of ERT and HRT. Therefore, optimizing the clinical benefits of these regimens in postmenopausal women depends largely on promoting a healthy endothelium through life-style modifications that diminish coronary risk.

Arterial stiffness in postmenopausal women: determinants of pulse wave velocity

OBJECTIVE To investigate the degree and potential cardiovascular determinants of arterial stiffness, assessed by aortic pulse wave velocity (PWV) measurements, and to relate arterial stiffness to absolute 10-12-year risks of stroke, coronary heart disease and death, as estimated by available risk functions, in postmenopausal women. METHOD We performed a cross-sectional study among 385 postmenopausal women, aged 50-74 years, sampled from the general population. Arterial stiffness was assessed non-invasively by measurement of aortic PWV using applanation tonometry. Information on health was obtained by medical history, registration of current medication, and physical examination. Height, weight, waist and hip circumferences, fasting glucose, total and high-density lipoprotein (HDL) cholesterol, triglycerides, resting blood pressure, and heart rate were measured. Three risk scores were used to estimate, for each individual, the absolute risk of stroke, coronary heart disease, and death within 10-12 years as a function of their cardiovascular risk factor profile. The relationship between PWV and these risk scores was subsequently determined. RESULTS Significant positive relationships with PWV were found for body mass index, fasting glucose, diabetes mellitus, and triglycerides in analyses adjusted for age, mean arterial blood pressure, and heart rate. Height and HDL cholesterol were inversely related to PWV. The risks of stroke, coronary heart disease, and death increased with increasing PWV in a linear graded manner. CONCLUSIONS This cross-sectional study among postmenopausal women provides evidence that most of the established cardiovascular risk factors are determinants of aortic PWV. Increased PWV marks an increased risk of stroke, coronary heart disease, and death within 10-12 years.

The carotid artery as a noninvasive window for cardiovascular risk in apparently healthy individuals

Cardiovascular diseases are the leading cause of death and disability in industrialized countries. Because the etiologies are related to alteration of arterial wall properties, the noninvasive evaluation could help the presymptomatic diagnosis and potentially the prevention of future events. Ultrasound (US) is currently the only modality to image the arterial wall in real-time with sufficient resolution to allow for observation of its morphological, hemodynamic and elastic properties. Increased wall thickness and atheromatous plaques of carotid arteries are associated with cardiovascular risk factors and diseases. Also, carotid Doppler waveforms and wall elasticity may have associations with arterial health. Although evaluation of these arterial properties are currently limited to the research laboratories, most of such properties can be evaluated in the standard setting of carotid ultrasonography. This article reviews "potential" utilities of carotid US evaluation for cardiovascular risk assessment in apparently healthy individuals.

Effects of oestrogen replacement on steady and pulsatile haemodynamics in ovariectomized rats

1. The effects of ovariectomy (Ovx), menopause and oestrogen replacement on the haemodynamics remain controversial. The present study employed the technique of arterial impedance analysis to measure and calculate the steady and pulsatile haemodynamics. The purpose was to determine the haemodynamic consequence of ovariectomy and oestrogen replacement. 2. Ovariectomy was carried out under anaesthesia on female Sprague Dawley rats aged 9 weeks. Oestrogen (17 beta-estradiol or E(2)) replacement started 1 week after ovariectomy for 4 weeks. Ovx increased the body weight (BW), while it greatly reduced the uterus weight. Left ventricular weight (LVW) was slightly increased, but LVW/BW ratio was slightly reduced. These changes were reversed after E(2) replacement. 3. Compared to sham group, Ovx with or without E(2) replacement did not significantly affect the systolic, mean and diastolic pressure. In Ovx, pulse pressure (PP) and heart rate were significantly increased, while stroke volume and cardiac output were slightly decreased. Total peripheral resistance (TPR) was largely elevated, indicating Ovx induced systemic vasoconstriction. These changes all returned to close normal values (sham group) after E(2) replacement, except PP. 4. Ovx increased the characteristic input impedance (Zc) and pulse wave reflection, while it decreased arterial compliance. E(2) treatment reversed these changes, except Zc. 5. These results demonstrate that Ovx influences both the resistance and Windkessel functions of the artery. E(2) treatment effectively reverses most the effects of Ovx both on the steady and pulsatile haemodynamics.

The effect of hormone replacement therapy on arterial blood pressure and vascular compliance in postmenopausal women with arterial hypertension

Arterial pathology is a major contributor to cardiovascular disease, morbidity and mortality. Women are at higher risk of cardiovascular disease after menopause. Arterial stiffness determined by pulse wave velocity, increases with age both in men and women, whereas arterial compliance in premenopausal women is greater than in men of similar age. This difference is lost in the postmenopausal years, with evidence of rapid decline in arterial compliance in the perimenopausal period. Loss of hormonal modulation is a likely explanation for reduced arterial compliance in postmenopausal women. Long-term treatment with hormone replacement therapy (HRT) may be expected to partially reverse the increase in arterial stiffness. The aim of the study was to analyse the effect of HRT on blood pressure and arterial compliance in postmenopausal women with arterial hypertension receiving hypotensive drugs. The results in the present study of postmenopausal women with mild to moderate arterial hypertension receiving HRT showed only a transient tendency towards lower blood pressure. In our study HRT was found to improve arterial compliance at 3 months after HRT, and the effect was maintained throughout 12 months. The increased arterial compliance in women receiving HRT was independent of blood pressure. In parallel with decreasing pulse wave velocity women receiving HRT had lower total and low-density lipoprotein cholesterol. The conclusions were that after 1 year HRT in postmenopausal women with arterial hypertension improves circadian blood pressure pattern, but it does not affect significantly blood pressure values and variability. The present study also shows that HRT significantly inhibits age-related rigidity of large arteries.

Sex hormone replacement therapy reverses altered venous contractility in rats after pharmacological ovariectomy

OBJECTIVE

Female sex hormones have several important effects on the venous system. We earlier found that hormone replacement has a significant effect on venous distensibility, but effects of menopause and hormone replacement on venous contractility have never been studied. Therefore, and because the changes we found earlier in distensibility were most likely caused by alterations of contractility, we examined the changes in contractility of saphenous vein caused by depletion and replacement of sex hormones in female rats.

DESIGN

Twenty Sprague-Dawley rats were pharmacologically ovariectomized by triptorelin. Ten of these rats received combined sex hormone replacement (HRT) with estradiol propionate and medroxyprogesterone acetate. The rest were given vehicle. Ten animals without ovariectomy served as controls. After 3 months of treatment, segments of the saphenous vein were dissected. Pressure-diameter curves were recorded in relaxed, contracted, and control states.

RESULTS

Venous diameter, adjusted for body weight, was significantly decreased after pharmacological ovariectomy. HRT increased the diameter. The presence of sex hormones augmented norepinephrine contraction measured at physiological pressures (control: 19.2 +/- 2.3%; pharmacological ovariectomy: 15.2 +/- 1.4%, p < 0.05 and 17.8 +/- 2.2% following HRT). Myogenic (spontaneous) tone of the saphenous vein did not change after ovariectomy, but it was lowered by hormone replacement (control: 8 +/- 1.1%; ovariectomy: 6.9 +/- 2.5%; ovariectomy + HRT: 2.7 +/- 1.1%, p < 0.05).

CONCLUSIONS

Sex hormone depletion induces significant alterations in contractility of the saphenous vein, which could perturb venous capacitance function and distensibility. This effect has a potential role in the development of hypertension and venous varicosity, and these changes could possibly be prevented by HRT.

Arterial stiffness is not improved in long-term use of estrogen

OBJECTIVE

The purpose of this study was to compare arterial stiffness in long-term users of estrogen who were postmenopausal, age-matched women who did not use estrogen, and women of fertile age.

STUDY DESIGN

In this clinical cross-sectional study, carotid, femoral, and aortic stiffness (estimated as elastic modulus and stiffness beta index) were assessed by ultrasonic phase-locked echo-tracking in 17 women who were postmenopausal and who were treated with 17 beta-estradiol implants (mean age, 68.8 years; mean duration of treatment, 20 years), 17 age-matched (+/-1 year) untreated women, and 20 women in the fertile age period.

RESULTS

Compared with women of fertile age, both postmenopausal groups had significantly higher stiffness elastic modulus and stiffness beta index (carotid, P <.001; femoral, P <.05; aorta, P <.001). However, for all 3 arteries, both stiffness indices were similar in estrogen users and nonusers and did not differ significantly. These results remained after an adjustment for systolic blood pressure, body mass index, and low-density lipoprotein cholesterol levels.

CONCLUSION

These data indicate that the arterial stiffening that is related to aging/menopause is not substantially affected by long-term estrogen therapy.

Menopause, estrogen, and training effects on exercise hemodynamics: the HERITAGE study

PURPOSE

To investigate the influences of menopause, hormone replacement, and endurance exercise training on cardiovascular hemodynamics and oxygen uptake parameters during exercise in women.

METHODS

Subjects were 338 premenopausal women, 29 postmenopausal women taking hormone replacement, and 28 postmenopausal women not taking hormone replacement, all enrolled in the HERITAGE Family Study. Hemodynamic and oxygen uptake data were gathered on a cycle ergometer at 50 watts (W), 60% peak oxygen uptake, and at peak exercise, both before and after a 20-wk regimen of endurance exercise training on a cycle ergometer.

RESULTS

Systolic blood pressure (SBP) during peak exercise was found to be an average of 14 mm Hg less in postmenopausal women receiving hormones than in those not receiving hormones. Furthermore, menopause was associated with a 26.2 mm Hg higher SBP at 50 W power output, which remained physiologically significant after adjustment for age. At 50 W, postmenopausal women not taking hormones showed a 13.8 mm Hg greater training-induced reduction in SBP than those taking hormones.

CONCLUSION

It was concluded that hormone replacement may be associated with a vasodilatory reserve at high exercise intensities and that endurance exercise training elicits favorable hemodynamic and oxygen uptake adaptations during exercise that are, in most instances, independent of menstrual status or hormone replacement.

Influence of 17beta-oestradiol on blood pressure of postmenopausal women at high vascular risk

OBJECTIVES

It remains an unsolved issue whether hormone replacement therapy (HRT) lowers blood pressure. This randomized trial examined the effect of 17beta-oestradiol combined cyclically with gestodene on blood pressure of postmenopausal women who were not on antihypertensive medication. All subjects had an increased risk for adverse vascular events as indicated by intima-media thickness of carotid arteries and standard risk factors.

DESIGN AND SETTING

Two hundred and twenty-six postmenopausal women were randomized to oral treatment for 48 weeks with 1 mg of 17beta-oestradiol per day continuously, plus 0.025 mg gestodene on days 17-28 of each 4-week cycle (HRT 1), or plus gestodene in each third cycle only (HRT 2), or no HRT. According to predefined criteria, four subjects in HRT 1, 12 in HRT 2 and 13 in no HRT who were started on antihypertensive medication were excluded from the analysis. Thirty subjects ended participation prematurely for other reasons. Resting blood pressure was measured at baseline and after 12, 22 and 48 weeks.

RESULTS

During treatment diastolic blood pressure changed significantly in both HRT groups compared to no HRT, by -3.7 +/- 9.8 mmHg, -3.0 +/- 8.8 mmHg and 1.0 +/- 9.9 mmHg at week 48 in groups HRT 2, HRT 1 and no HRT, respectively (P = 0.008 for HRT 2 versus no HRT, P = 0.027 for HRT 1 versus no HRT). The higher the diastolic blood pressure was at beginning the greater was the decrease. The decrease of systolic blood pressure was not significantly different between groups.

CONCLUSIONS

For postmenopausal women with high cardiovascular risk but without antihypertensive medication, long-term treatment with 17beta-oestradiol combined with gestodene lowers diastolic blood pressure.

Sex hormone replacement therapy reverses decreased venous distensibility in pharmacologically ovariectomized rats

OBJECTIVE

To test the effect of female sex hormone depletion and replacement on the distensibility and geometry of the saphenous vein in female rats.

DESIGN

Twenty Sprague-Dawley rats were pharmacologically ovariectomized by triptorelin. Ten of these animals received combined hormone replacement with estradiol and medroxyprogesterone acetate. The rest were given vehicle. Ten animals kept parallel without pharmacological ovariectomy served as controls. After 3 months of treatment, a segment of the saphenous vein was dissected. Pressure-diameter curves were recorded in relaxed, contracted, and control states using a microangiograph.

RESULTS

Pharmacological ovariectomy lowered venous wall distensibility measured in contraction (at P=8 mm Hg: 4.41+/-1.21*10(-3) m2/N vs. control: 0.79+/-0.14*10(-3) m2/N; p < 0.05). Hormone replacement partially restored this value (1.8+/-0.49*10(-3) m2/N). No alterations in distensibility were found in the relaxed state. After adjusting for body weight, we found that pharmacological ovariectomy lowered venous inner radius significantly compared with control (p < 0.05), whereas hormone replacement increased it compared with pharmacological ovariectomy (p < 0.05) and more significantly compared with control (p < 0.01).

CONCLUSION

Sex hormone depletion induces significant alterations in venous distensibility, presumably by inducing initial remodeling of the venous wall. Hormone dependency of distensibility differed in relaxed and contracted states of the vein, so some alterations of contractile elements of the wall may be hypothesized. Lower distensibility of the venous wall found after pharmacological ovariectomy could be part of the mechanism of predisposition for postmenopausal hypertension. This can be reversed by female sex hormone replacement.

Effect of estrogen replacement therapy on insulin sensitivity of glucose metabolism and preresistance and resistance vessel function in healthy postmenopausal women

In the present study, we hypothesized that estradiol, via its ability to vasodilate in an endothelium-dependent manner, might enhance vascular effects of insulin. Basal and insulin-stimulated peripheral blood flow and resistance, arterial stiffness, and glucose metabolism were determined in 27 healthy postmenopausal women before and after 12 weeks of treatment with either transdermal or oral estradiol or corresponding placebo preparations. Whole body insulin sensitivity was determined using the euglycemic insulin clamp technique (rate of continuous insulin infusion 1 mU/kg.min), forearm blood flow with a strain-gauge plethysmography, and arterial stiffness using pulse wave analysis. Estradiol therapy increased basal peripheral blood flow (1.5 +/- 0.1 vs. 1.9 +/- 0.1 mL/dL.min, 0 vs. 12 weeks; P: < 0.01), decreased peripheral vascular resistance (65 +/- 3 vs. 52 +/- 3 mm Hg/mL/dL.min, respectively; P: < 0.01), and diastolic blood pressure (78 +/- 2 vs. 75 +/- 2 mm Hg, respectively; P: < 0.05) but had no effect on large artery stiffness. Infusion of insulin did not acutely alter peripheral blood flow but diminished large artery stiffness significantly both before and after the 12-week period of estradiol therapy. No measure of acute insulin action (glucose metabolism, blood flow, or large artery stiffness) was altered by estradiol or placebo treatment. These data demonstrate that insulin and estradiol have distinct hemodynamic effects. Physiological doses of estradiol increase peripheral blood flow but have no effects on large artery stiffness, whereas physiological concentrations of insulin acutely decrease stiffness without changing peripheral blood flow. Putative vasculoprotection by estradiol is, thus, not mediated via alterations in arterial stiffness or insulin sensitivity.

Estrogen replacement reduces age-associated remodeling in rat mesenteric arteries

Estrogen replacement therapy significantly decreases the incidence of cardiovascular disease in postmenopausal women. In aging, there is an increase in vascular stiffness along with a decrease in matrix metalloproteinase (MMP) activity. Our hypothesis was that estrogen replacement would increase MMPs and therefore reduce the vascular stiffness that is associated with aging. Female Sprague-Dawley rats were implanted with a placebo or 17ss-estradiol-containing pellet (0.5 mg/pellet, 60-day release) at 10 months of age (n=6, each). Six young rats (3 months old) were also studied. After a 2-month exposure to the pellet, mesenteric arteries were studied on a pressurized arteriograph system. Distensibility and wall thickness were measured in response to stepwise increases in intraluminal pressure in Ca(2+)-free physiological saline solution buffer with papaverine (10(-4) mol/L). In response to increasing pressure, aged placebo rats exhibited a significant decrease in distensibility compared with young rats (P<0.05) that was accompanied by an increase in wall thickness (P<0.05). Conversely, estrogen replacement increased distensibility and decreased wall thickness in aged rats (old estrogen-replaced versus old placebo, P<0.05). Zymography data indicated that MMP-2 activity decreased in aging but was increased by estrogen replacement. In summary, estrogen replacement in aging female rats reduces age-associated vascular remodeling.

Hormone replacement therapy and distensibility of carotid arteries in postmenopausal women: a randomized, controlled trial

OBJECTIVES

The study objective was to clarify in a randomized, controlled, observer-blind trial whether hormone replacement therapy (HRT) improves elastic properties of the common carotid artery in women with signs of subclinical atherosclerosis, especially in subgroups with increased risk, and whether less progestin enhances the effect.

BACKGROUND

Previous observational studies have yielded conflicting results on the influence of HRT on central arteries. Some studies reported improvement of distensibility by estrogen alone or in the subgroup of smokers.

METHODS

A total of 321 postmenopausal women were randomized to 1 mg 17beta-estradiol plus 0.025 mg gestodene for 12 days every month (HRT 1), or 1 mg 17beta-estradiol plus 0.025 mg gestodene for 12 days every third month (HRT 2), or no-HRT, during 48 weeks. In 173 women, distensibility of the common carotid artery was determined before and after therapy by M-mode ultrasound and brachial blood pressure measurement.

RESULTS

Change of distensibility was small and similar in the three treatment groups. In the subgroup of current smokers, HRT 2 (low progestin) increased distensibility by 32% (HRT 2: 8.2+/-11.7; HRT 1:0.6+/-6.0; no HRT: -1.8+/-6.8 x 10(-3)/kPa, p = 0.025 for no-HRT vs. HRT 2). In the subgroups with elevated blood pressure, high low density lipoprotein (LDL) cholesterol, or high age, no effect of HRT was detected.

CONCLUSIONS

This randomized intervention study demonstrates that long-term HRT with estrogen and progestin does not substantially influence distensibility of central arteries. Yet, in currently smoking postmenopausal women, HRT with low progestin seems to improve distensibility; this merits further study in a specifically designed trial.

Effect of ovariectomy and hormone replacement therapy on small artery biomechanics in angiotensin-induced hypertension in rats

OBJECTIVES

To test the effects of chronic angiotensin II administration on blood pressure and small artery biomechanics in the female sex hormone-depleted state (proposed to increase cardiovascular vulnerability) and with hormone replacement.

DESIGN

Biomechanical properties of saphenous artery segments from ovariectomized (n = 10), ovariectomized + chronically angiotensin II infused-(n = 10), and ovariectomized + chronically angiotensin II-infused + sex hormone-replaced (n = 10) rats were studied.

METHODS

Surgical ovariectomy was performed. Osmotic minipumps were used for chronic angiotensin II infusion (100 ng/min per kg). For hormone replacement therapy, oestradiol-propionate, 450 microg/kg for 7 days + medroxyprogesterone-acetate, 15 mg/kg for 14 days were given, intramuscularly. After 4 weeks, cylindrical segments of the saphenous artery were prepared and subjected to in-vitro microarteriographic measurements. Pressure-diameter curves (0-200 mmHg) were recorded in Krebs-Ringer solution, with smooth muscle contracted (norepinephrine, 16 micromol/l) and with relaxed (papaverine, 28 micromol/l).

RESULTS

Chronic angiotensin II infusion significantly reduced the inner radius (at 100 mmHg: 298 +/- 17 microm versus 347 +/- 7 microm, P< 0.001), while wall-thickness did not change. Hormone replacement restored the morphological radius (333 +/- 7 microm). Angiotensin II infusion slightly increased the full contraction range of the segments (defined as the percentage difference between fully contracted and fully relaxed diameters), which was further significantly increased by hormone replacement (39 +/- 4%, 46 +/- 8%, 62 +/- 7% at 100 mmHg, in the three groups, respectively; P < 0.05). Despite unaltered stiffness in relaxed state, elastic moduli computed for the contracted segments decreased after hormone replacement.

CONCLUSIONS

These observations give further experimental support to the hypothesis that sex hormone replacement might be useful in preventing the development and/or stabilization of postmenopausal hypertension, as well as in treating existing disease.